1. Field of the Invention
The invention concerns a grip for a tubular shafted surgical instrument having two grip parts. The grip parts have grip contact surfaces which run generally parallel to each other and to the shaft tube. The first grip part is securely attached to the shaft tube, while the second grip part is pivotable as a rocker and engages the operational element of the tubular shaft instrument.
2. Description of the Related Art
Tubular shaft instruments of many types are used in arthroscopic and in minimally invasive surgery. The tubular shafted instruments are comprised of a tubular shaft in which an operative element is axially slidably mounted. The axial sliding of the operative element with respect to the tubular shaft results in operation of the jaws which are provided on the distal end of the tubular shafted instrument, that is, in general operating brings about a closing of the jaws. The operation of the jaws can be accomplished by a pushing of the operational element within the tubular shaft, for which the operational element must have sufficient stiffness, for example, as a rod or internal tube. If the operation of the jaws is accomplished by an axial pulling of the operational element, then such a stiffness of the operational element is not required, and the construction of the operational element is not limited to a rod or internal tube, but can be constructed of a flexible draw cable.
The known tubular shafted instruments are comprised, in most cases, of a scissor grip with two ring-grip parts which are pivotally mounted with respect to each other. The first grip part is fixedly connected to the tubular shaft, while the second grip part is connected to the operational element. The two grip parts are offset at an angle of up to 90.degree. relative to the axis of the tubular shaft, and lie in the plane of operational movement of the jaws of the tubular shaft instrument. Should it be necessary during operation to change the operational plane of the jaws, for example the plane of the cutting or gripping action of the jaws, then the operator must correspondingly twist the hand which is manipulating the controls. This can lead to an ergonomicaly uncomfortable hand position, which in particular in lengthy operations can lead to significant fatigue. For operating the jaws of the tubular shaft instrument the grips are moved towards each other under pressure. For the opening of the jaws the rings, in which the fingers of the operator are inserted, are forced apart. In the course of such an opening movement it is very difficult to stably manipulate the tubular shaft instrument and particularly the jaws.
There are also known scissor grips with ringless grip parts, in which the grip parts are pressed towards each other for the operation of the jaws, and in which for the opening movement they are spread apart by means of a spring mechanism. When using such an instrument it is necessary to almost completely relax the grip in order to permit the jaws to open, so that the controlling of the instrument is even more difficult.